2001 e320 4matic wagon about 120k mi.

My daughter uses it mostly, has had a couple episodes of not starting - cranked but no start, tried a couple of times then started. Usually has check engine light after this which goes away in a day or so...

Checked battery voltage car off no load got 12.5v. I believe this may indicate a battery on the way out? And low battery can cause a variety of similar simptoms?

Otherwise cam position sensor?
I know I should get a code reader, will order one of the ones that cost about 155 launch creamer vII + that should read most codes.

Any advise - should I go ahead and get a new battery?
Thanks
Paul

12.5 is just under 100% charged for a battery that has been sitting 8 hr without being charged / discharged. ( 12.66 is theoretical full charge but that can vary. )

What sort of voltage do you get while cranking
?

I've had batteries with good open circuit voltage but it dips too low under a load. How far the voltage drops depends on the load applied

You need to see what the trouble code is before going farther.

Also, a weak battery / bad connection isn't the best thing for a smart key, if the voltage droops too far during the key read write sequence, the system can brick. And of course , many blame the act of jump starting even though the damage was there before jump starting.

Cranking no-start, esp. when warm, is often a crank position sensor on the M112/113. Typically though the car stalls and then can be restarted after cooling down.

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Prost!

+1 I had a bad crank position sensor a couple of times on my '99. You need a female torx socket (maybe E8?) to replace it, otherwise it's a five minute procedure.

I don't think a failing crank position sensor would trigger the CEL light

__________________
-- raymond~
47º 34'N 122º 18'W

Ok thanks for the inputs. A bit more info as I took it out intending to run an errand. Measured voltage again - no load 12.4v, Started normally (voltage at battery - it's a wagon- after start was 14.17v using a crappy digital multimeter) drove for about 3 mi and it died while driving, no symptoms aside from engine stopping rpm on tach drop to zero and I believe most dash lights light up. Pulled over shut down and try to restart engine spins for a couple seconds no start, did this about 4 times, got it started (gave some gas while turning over, not sure if that made a difference ). After restart only warning is CEL, drove home and parked it for the moment.

So does any of this help without codes?
Maybe separate topic but is the launch reader worth getting - does it rad most subsystems through the obd2 port as it does not come with a 38 pin adapter. If not should I just get a cheap one for the moment? Will take a bit for the launch one to arrive if I go that route, if I buy a cen tec (horrible freight special or similar) may be able to get it tomorrow.

Wild ass guesses? Figure could be fuel filter related?, CPS as suggested, brake switch, voltage running seems a bit high, have the same car in a 2002 version so can check that, voltage regulators are relatively cheap although not sure that would cause any of these symptoms...

Thanks
Paul

It did when mine failed, but I don't think it always does.

__________________
Prost!

Charging voltage is on the low side of good but nowhere near causing a problem. The voltage would pickup after the battery if fully charged and might hit 14.7

Most torx bolts that need a " M " female socket can be removed with regular 6 point sockets, the fit is very good.

Don't randomly throw parts at this car, see what the codes say. Now, I do however change parts when they get towards the end of their expected life. The crank sensor is one of these items I change at your time and mileage.

My specific experience with this specific car is that the CPS is a frequent problem, but checking the codes would tll you for sure.. My specific experience with fasteners if all types is that its better to use the right tool than to get cheap and deal with rounded heads.

For a very high torque app I'd use the E socket, however for valve cover , intake manifold and other general fasteners, a regular 6 PT works, a fresh sharp 12 would probably work too but that may be pushing it.

Many times E torx is used to reduce head / socket diameter for extra clearance.

Using this calculator to convert point to point to nominal across flats of a 6 pt socket.

Hexagon Measurement Calculator


And this chart

Typical Dimensional and Torque Specifications of TORX Tools

Point to point measurement ( Calculated across flats in red )
Socket E-Size Inch Metric
E-4 .150" 3.83mm .130" 3.31 mm
E-5 .185" 4.72mm .160" 4.08 mm 5/32 is 0.156"
E-6 .225" 5.69mm .195" 4.92 mm 3/16 is 0.188"
E-7 .241" 6.17mm .208" 5.34 mm 13/64 is 0.203"
E-8 .292" 7.47mm .253" 6.47 mm 1/4 is 0.250"
E-10 .367" 9.37mm .319" 8.11 mm 5/16 is 0.313"
E-12 .436" 11.12mm .378" 9.63 mm 3/8 is 0.375"
E-14 .503" 12.85mm .436" 11.12 mm 7/16 is 0.438"
E-16 .576" 14.71mm .498" 12.74 mm 1/2 is 0.500"
E-18 .652" 16.64mm .565" 14.41 mm 9/16 is 0.536"
E-20 .722" 18.41mm .625" 15.94 mm 5/8 is .625

OK got a el cheapo code reader for now. I figure I may pick up one of the Launch ones as they supposedly read the other systems and having that on hand is lily woirthwhile as we currently have 2 w210's

Anyway codes present were
P0335 CPS (as predicted)
P0120 throttle pedal position sensor
P0455 emissions system leak (likly cause of CEL)

Erased and restarted car nothing showed up on restart. Will prob show next time.
So my thought is order CPS
any thoughts on throttle pedal position sensor?

Thanks
Paul

This is just my opinion: the CKP is a common failure item, actually should be thought of as preventive maintenance in my book, and cheaper, so I would just replace that with a new one first.
The TPS should give other symptoms like stumbling or poor throttle response, so it may be an old or spurious code. I would reset the code and wait to see if it reappears.

__________________
Prost!

maybe i should buy 2 as we also have a 2002 w210 wagon that I dont think the CPS hase ever been changed about 230K mi....

paul

did have it go into limp mode once about 6 months ago after stepping on the throttle (aggressively - floored...) to pass. n probably should try that a few times in the future.

Thanks
Paul

The crank sensor was probably becoming erratic before failure tripping the code. It's a safe bet to change it.

The throttle position code could have been a byproduct of the crank sensor but we would need a detailed code description and exactly what conditions cause it to trigger.

The emissions leak is the fuel evaporative system. Could have been a gas cap left off / bad or a leak in the hoses.